Find in Library

<i>Gelsemium elegans</i> <i>Benth</i>. (GEB) is a traditional medicinal plant in China, and acts as a growth promoter in pigs and goats. Koumine (KM) is the most abundant alkaloid in GEB and produces analgesic, anti-cancer, and immunomodulatory effects. KM can be used as an aquatic immune stimulant, but its growth-promoting effects and transcriptional mechanisms have not been investigated. Diets containing KM at 0, 0.2, 2, and 20 mg/kg were fed to <i>Cyprinus carpio</i> for 71 days to investigate its effects on growth performance, intestinal morphology, microflora, biochemical indicators, and transcriptional mechanisms. <i>Cyprinus carpio</i> fed with KM as the growth promoter, and the number of intestinal crypts and intestinal microbial populations were influenced by KM concentration. KM increased the abundance of colonies of <i>Afipia</i>, <i>Phyllobacterium</i>, <i>Mesorhizobium</i>, and <i>Labrys</i>, which were associated with compound decomposition and proliferation, and decreased the abundance of colonies of pathogenic bacteria <i>Methylobacterium-Methylorubrum</i>. A total of 376 differentially-expressed genes (DEGs) among the four experimental groups were enriched for transforming growth factor-β1 and small mother against decapentaplegic (TGF-β1/Smad), mitogen-activated protein kinase (MAPK), and janus kinases and signal transducers and activators of transcription (Jak/Stat) signaling pathways. In particular, <i>tgfbr1</i>, <i>acvr1l</i>, <i>rreb-1</i>, <i>stat5b</i>, <i>smad4</i>, <i>cbp</i>, and <i>c-fos</i> were up-regulated and positively correlated with KM dose. KM had a growth-promoting effect that was related to cell proliferation driven by the TGF-β1/Smad, MAPK, and Jak/Stat signaling pathways. KM at 0.2 mg/kg optimized the growth performance of <i>C. carpio</i>, while higher concentrations of KM (2 and 20 mg/kg) may induce apoptosis without significantly damaging the fish intestinal structure. Therefore, KM at low concentration has great potential for development as an aquatic growth promotion additive.